Certain naturally occurring materials contain a carbonaceous component which, upon heating, will release a hydrocarbon product which is useful as a feedstock in petroleum processing. These "hydrocarbon-containing solids" such as oil shale and tar sands, including diatomite, may be pyrolyzed in reactor vessels having various designs. Prior to being pyrolyzed the solids are usually reduced to a particulate material by crushing, grinding, etc. During this step, a substantial amount of fines are produced which are readily entrained by the stripping gas which is employed in the reactor vessel to carry off the product vapors. As a result, the attrition rate of these fines in the reactor vessel is usually very high, and the fines may be carried away from the pyrolysis zone before they have had the opportunity to completely release their hydrocarbons, i.e., before they are completely pyrolyzed. In most processes, the hydrocarbons contained in these unpyrolyzed or partially pyrolyzed fines are never recovered as product.
The present invention is directed to an improved process which makes it possible to recover the hydrocarbons in the fines which would normally be lost.